Secretion in the epididymis will be studied by completing analysis of electron microscope radioautographs of mouse epididymides labeled with leucine-3H. Preliminary in vitro studies on labeling of epididymal secretions will be conducted. The relation between cell types in the epididymal epithelium of the rat will be explored by attempting to modulate cell types using surgical methods and drugs. The structure and function of the efferent ducts of the rat will be studied by extending current experiments on the fate of absorbed electron-opaque tracers and by the use of electron microscope cytochemical staining methods. Investigation of the influence of the antiandrogen, Flutamide, on the male reproductive tract of the rat is planned.